Cliff's - the slotted foam is great. The Beast and Beast Jr are do a good job holding your "beach sized" flies and not squishing them flat. Cliff's also has a large waterproof box (the Justin Case).

I have never seen "Bug Luggage" before. They look great for small stuff. BugLug website makes it sound like their larger boxes are not that tall. I suspect they would cause problems with your PINS flies.

I would buy a box of each brand and figure out what works for you. You can give me whichever one you don't want.